class student:
    cls = 'QC5'
    def __init__(self,name):
        self.name = name

if __name__ == '__main__':
     s1 = student('张三')
     s2 = student('李四')

     print(s1.name)

     s1.age = 20
     print(s1.age)

     s1.name = '张三丰'
     print(s1.name)

     del s1.age

     print(s1.cls)
     print(student.cls)

     student.cls = "qwer"
     print(student.cls)
     print(s1.cls)

     print(student.__dict__)
     print(s1.__dict__)

     del student.cls
     # print(student.cls)















